Popcorn: A snack, a dessert, and a movie-theater staple. Americans consume as much as 18 billion quarts of popcorn each year. It is loved by many, but do we even know how it works?Popcorn pops open at temperatures above 180 degrees Celsius. Its three parts include the pericarp, the germ (the seed embryo), and the endosperm. The endosperm holds water, and when the popcorn is heated, it is turned into steam. Pressure builds, and suddenly, POP! The strong pericarp is ruptured, and gelatinous starch solidifies into the white shape that we all know and love.