A popcorn kernel is essentially a sealed container efficiently storing moisture, and the makings of a new plant. When enough heat is applied to a kernel, the internal moisture is turned into steam, and because steam takes up more space than water, the small shell cannot contain it, so it rapidly expands, creating a tiny, but powerful, “POP”.
Traditional popcorn is called butterfly or snowflake because it has “wings,” and pops into different shapes. Popcorn that pops large and round without a lot of extensions is called mushroom popcorn. This is the kind that is often glazed or coated and sold as flavored, gourmet popcorn.