question: when popping popcorn, why does the first kernel popped not burn while the others are being popped?
comment: Some general background: Boiling water in a pot is always (usually) at 100 deg C or 212 F. When boiling or steaming food, the phase change from liquid to vapor controls the cooking temperature, until there is no more water. As applied to popping corn, the microwave, stove or kettle heats the water in the kernel and when it boils, the kernel pops. When the majority of the kernels are unpopped or actively popping, the temperature is relatively controlled, so the first kernels aren't burning. When the last few kernels are popping or popping is complete there is less water becoming steam to moderate the temperature, and the corn increases temperature rapidly and it is more likely to burn. Edited for clarity, apparently some thought I was making a case for boiling corn kernels in water. Probably moved it out of an eli5 though. Edit 2: some awesome discussion downline of granular convection, actual temps for popping and so forth. All have impacts on why the first popper doesn't burn. I contend latent heat of evaporation and escaping steam and resulting loss in temp moderation is the main driver in why popcorn goes from just popping to inedible so quickly
passages: When the popcorn has finished popping, sometimes unpopped kernels remain. Known in the popcorn industry as "old maids", these kernels fail to pop because they do not have enough moisture to create enough steam for an explosion. Re-hydrating prior to popping usually results in eliminating the unpopped kernels.
   Popping results are sensitive to the rate at which the kernels are heated. If heated too quickly, the steam in the outer layers of the kernel can reach high pressures and rupture the hull before the starch in the center of the kernel can fully gelatinize, leading to partially popped kernels with hard centers. Heating too slowly leads to entirely unpopped kernels: the tip of the kernel, where it attached to the cob, is not entirely moisture-proof, and when heated slowly, the steam can leak out of the tip fast enough to keep the pressure from rising sufficiently to break the hull and cause the pop.
   The design of a microwave popcorn bag is specifically keyed to avoid popped kernel scorching, an undesirable effect that takes place when popped kernels are heated above .
   Popcorn will pop when freshly harvested, but not well; its high moisture content leads to poor expansion and chewy pieces of popcorn. Kernels with a high moisture content are also susceptible to mold when stored. For these reasons, popcorn growers and distributors dry the kernels until they reach the moisture level at which they expand the most. This differs by variety and conditions, but is generally in the range of 14–15% moisture by weight. If the kernels are over-dried, the expansion rate will suffer and the percentage of kernels that pop will decline.
   A susceptor, usually a metalized film laminated onto the paper of the bag, absorbs microwaves and concentrates heat at the film interface, thus ensuring a heat distribution focused on the hard-to-heat flavor coating so that the unpopped kernels are evenly coated prior to popping, thereby ensuring even flavor throughout the product. Additionally, some popcorn is flawed and will not pop because of possible damage to the shell, which allows the steam to escape. These unpopped kernels are known as "old maids" or "spinsters".
   As the oil and the water within the kernel are heated, they turn the moisture in the kernel into pressurized steam. Under these conditions, the starch inside the kernel gelatinizes, softens, and becomes pliable. The internal pressure of the entrapped steam continues to increase until the breaking point of the hull is reached: a pressure of approximately and a temperature of . The hull thereupon ruptures rapidly and explodes, causing a sudden drop in pressure inside the kernel and a corresponding rapid expansion of the steam, which expands the starch and proteins of the endosperm into airy foam. As the foam rapidly cools, the starch and protein polymers set into the familiar crispy puff. Special varieties are grown to give improved popping yield. Though the kernels of some wild types will pop, the cultivated strain is "Zea mays everta," which is a special kind of flint corn.
   In the "MythBusters" episode, "Car vs. Rain", first broadcast on June 17, 2009, the "MythBusters" team tried to determine whether the final scene in the film, the destruction of Dr. Hathaway's house with laser-popped popcorn, is actually possible. First they used a ten-watt laser to pop a single kernel wrapped in aluminum foil, showing that popping corn is possible with a laser, then they tested a scaled-down model of a house. The popcorn was popped through induction heating because a sufficiently large laser was not available. The result was that the popcorn was unable to expand sufficiently to break glass, much less break open a door or move the house off its foundation. Instead, it ceased to expand and then simply charred.
   A safety issue is that the cooking time given on the packaging does not apply to all microwave ovens. Setting the timer and coming back later, after the timer's alarm has sounded, could result in the popcorn being burnt and smoking badly. Microwave popcorn makers suggest that the person cooking the popcorn stay near the oven to observe the popcorn as it cooks, and take the popcorn out when the time between pops is more than a few seconds.
   The corn grown by Kelty was never hybridized or genetically modified. Kelty's stalks would reach a height of four to five feet. Each kernel was capable of producing four to six stalks with three to four ears of corn each, unlike field corn. Each ear of corn was grown to be less than three inches long. The characteristics of Kelty's popcorn were created through open pollination, seed selection, and roguing.
  
  Section::::History.:Mealhow purchase.
   The heat and pressure force the gases to react with each other, and at the end of the spark event there should be a small ball of fire in the spark gap as the gases burn on their own. The size of this fireball, or kernel, depends on the exact composition of the mixture between the electrodes and the level of combustion chamber turbulence at the time of the spark. A small kernel will make the engine run as though the ignition timing was retarded, and a large one as though the timing was advanced.
  
  Section::::Spark plug construction.
   for every pair of players "i" and "j". Intuitively, player "i" has more bargaining power than player "j" with respect to imputation "x" if formula_156, but player "j" is immune to player "i"'s threats if formula_157, because he can obtain this payoff on his own. The kernel contains all imputations where no player has this bargaining power over another. This solution concept was first introduced in .
  
  Section::::Solution concepts.:The nucleolus.
   During the 1990s, Gene Mealhow, another eastern Iowa farmer, was working as a soil consultant. Mealhow and his wife, Lynn, had been growing organic crops on their farm since 1989. Gene Mealhow met Kelty in the early 1990s, and they worked together to improve Kelty's popcorn crop. The Mealhows purchased the company on July 1, 1999, allowing Kelty to retire. Kelty said about the Mealhows, "They embrace the concept of having this direct relationship between the customer and the producer that I think is so important for this product." At that time, the company had of land for popcorn crops. After the Mealhows purchased the company, they moved its processing equipment from the Kelty farm in Urbana to their own farm north of Shellsburg, Iowa.
   At the time of the Mealhow purchase, K&K Popcorn was sold through Fareway stores. The Mealhows were initially unsuccessful in convincing Whole Foods Market to carry their product. One store manager in Chicago ultimately agreed to stock the product for a month; the manager contacted the family 10 days later to request additional stock after it sold out. The company's popcorn was eventually carried in every Whole Foods store in Chicago. By 2000, the company's popcorn was advertised as being the world's smallest; Gene Mealhow stated, "The smaller the kernel, the better the flavor."
   Popping of the kernels was achieved by hand on the stove-top through the 19th century. Kernels were sold on the East Coast of the United States under names such as "Pearls" or "Nonpareil". The term "popped corn" first appeared in John Russell Bartlett's 1848 "Dictionary of Americanisms". Popcorn is an ingredient in Cracker Jack, and in the early years of the product, it was popped by hand.
   Corn on the cob is normally eaten while still warm. It is often seasoned with salt and buttered before serving. Some diners use specialized skewers, thrust into the ends of the cob, to hold the ear while eating without touching the hot and sticky kernels.
  
  Within a day of corn being picked it starts converting sugar into starch, which results in reduction in the level of natural sweetness. Corn should be cooked and served the same day it has been harvested, as it takes only a single day for corn to lose up to 25% of its sweetness.
  
  Section::::Preparation.
   Each kernel of popcorn contains a certain amount of moisture and oil. Unlike most other grains, the outer hull of the popcorn kernel is both strong and impervious to moisture and the starch inside consists almost entirely of a hard type.
   The fungus infects all parts of the host plant by invading the ovaries of its host. The infection causes the corn kernels to swell up into tumor-like galls, whose tissues, texture and developmental pattern are mushroom-like. These galls are made up of hypertrophied cells of the infected plant, along with resulting fungal threads, and blue-black spores. These dark-colored spores give the cob a burned, scorched appearance; this is the origin of the generic name "Ustilago", from the Latin word "ustilare" (to burn).
  
  Section::::Biology.
  
  Section::::Biology.:Life cycle.
   In 2003, Market Square Food Company Inc., based in Highland Park, Illinois, began purchasing raw popcorn from K&K Popcorn and popping it. The company would then package the popcorn under the label, "The World's Tiniest Popcorn We Think." Market Square's popcorn went on sale in Iowa in December 2003, and was available in four flavors. Stores also continued to sell K&K's un-popped popcorn, which at that time was made without preservatives, as well as artificial colors and flavors.
   The most common methods for cooking corn on the cob are frying, boiling, roasting, and grilling. Corn on the cob can be grilled directly in its husk, or it can be husked first and then wrapped in aluminum foil. When oven roasting, cooking the corn in the husk directly on the rack is recommended. When roasting or grilling corn on the cob, the cook can first peel the husk back to rub the corn with oil or melted butter, then re-secure the husk around the corn with a string. Corn on the cob can also be microwaved for 3 to 4 minutes still in its husk.
   Popcorn
  
  Popcorn (popped corn, popcorns or pop-corn) is a variety of corn kernel, which expands and puffs up when heated.
  
  A popcorn kernel's strong hull contains the seed's hard, starchy endosperm with 14–20% moisture, which turns to steam as the kernel is heated. Pressure from the steam continues to build until the hull ruptures, allowing the kernel to forcefully expand from 20 to 50 times its original size—and finally, cool.
   The new roaster was driven by a small steam engine, which automated the roasting process. By 1893, Cretors had created a steam powered machine that could roast peanuts as well as popcorn in oil. Cretors' machine design offered several advantages over the hand-operated process. Cretors’ machine became the first automated machine that could pop popcorn uniformly in its own seasonings. As a result, the product was uniform every time. Cretors applied for a patent on his automated peanut roaster and popcorn popper machine, which was granted in 1893.
   List of popcorn brands
  
  This is a list of notable popcorn brands. Popcorn, also known as popping corn, is a type of corn (maize, "Zea mays var. everta") that expands from the kernel and puffs up when heated. Popcorn is able to pop because its kernels have a hard moisture-sealed hull and a dense starchy interior. Pressure builds inside the kernel, and a small explosion (or "pop") is the end result. Some strains of corn are now cultivated specifically as popping corns.
   Since 1854, the ancestors of Richard Kelty (1936-2015) had been growing a heirloom popcorn variety out of small kernels, whose hulls would disintegrate after being popped, resulting in a richer taste. The popcorn had been introduced to the Kelty family by Native Americans, who shared it with them. The Kelty family had never sold the popcorn, which was only grown for personal consumption.
   In order to be elected governor, any gubernatorial candidate is required to obtain a statewide plurality of all votes cast in their election. Given the dominance of the two-party system in Kansas (between the Democrats and the Republicans), the plurality is often a majority as well. However, in the event that two or more candidates have an equal number of votes, the legislature, by joint ballot, elects one of those candidates governor.
   Section::::Uses.
  
  Section::::Uses.:Fodder (ensilaged or nonensilaged).
  
presuppositions: Cooking time causes popcorn to burn. The first kernel of popped popping corn does not burn while others are popping.
corrections: Cooking temperature causes popcorn to burn, not the cooking time. While it doesn't happen every time it is possible that the first kernel may burn near the ending of popping all popcorn kernels.
raw_presuppositions: Cooking time causes popcorn to burn. The first kernel of popped popping corn does not burn while others are popping. The first kernel of popped popping corn does not burn while others are popping.
raw_corrections: Cooking temperature causes popcorn to burn, not the cooking time. While it doesn't happen every time it is possible that the first kernel may burn near the ending of popping all popcorn kernels. The first kernal of popped popping corn may burn while others are popping.