CandyCritic sez, "The kernels are sealed in that thing he's spinning around. As they heat up they don't explode, because they're sealed with no air going in or out. He heats them up to a certain temperature and then he puts the sealed container with hot kernels into a bag. He then opens the container in the bag, allowing the kernels to expand, and every single kernel pops at the same time."
I write books. My latest is a YA science fiction novel called Homeland (it's the sequel to Little Brother). More books: Rapture of the Nerds (a novel, with Charlie Stross); With a Little Help (short stories); and The Great Big Beautiful Tomorrow (novella and nonfic). I speak all over the place and I tweet and tumble, too.