When they're in molten potassium chlorate, of course! This quick demonstration shows a gummy bear wailing away while setting off a fire that looks like the inside of the sun. All done with potassium chlorate and a test tube.
Potassium chlorate is that most sought-after material for all pyromaniacs, an oxidizer. It has a potassium atom, a chlorine atom, and three oxygen atoms per molecule, and it is very willing to lend those oxygen atoms out. In fact, all you need to do is melt it down, and all three of those oxygen atoms detach, leaving a solid salt of potassium and chlorine behind. (As it is melted, not all is broken down to gas and salt, just enough to make what happens next spectacular.)
If you were to add sugar to this mixture, you would have a miserable time. Some sugar molecules would react with the hot oxygen and burn. This burning sugar would fly through the air to touch the next bit of sugar, which would also burn. The entire thing would expand into a violent explosion. If only there were a source of firmly anchored sugar.
Enter the unfortunate gummy bear. The sugars in the gummy bear are all glued together. So when they come into contact with the oxygen and the extreme heat (potassium chlorate doesn't melt until it hits between three hundred fifty and four hundred degrees centigrade), the bear burns fast but stays together as it does. And when I say burns, I mean goes off like a road flare, but more violent. There is smoke, as the ash of the sugar escapes the tube, along with the rapidly expanding air. That expanding air, and the way it whistles through the tube and the decaying bits of gummy bear, can make a loud screaming sound, earning the entire experiment the morbid nickname, "The Screaming Gummy Bear."
In England, where they call gummy bears "jelly babies," the title of the demonstration sounds even more ghastly.
Via Digital Dapp.