If your childhood years happened to fall after 1975, then you’ve most likely tried Pop Rocks, and experienced the candy’s crackling fizziness when you put it in your mouth. But how exactly is this unique confection made?
Pop Rocks get its fizziness from the same thing that makes soda fizzy: carbon dioxide. In order to make Pop Rocks, sugar, lactose, and flavorings are melted down into a thick syrup, which is then blasted with pressurized carbon dioxide at about 600 pounds per square inch. The syrup is then dried, resulting in teeny tiny high pressure bubbles being trapped within the candy; if you look at Pop Rocks under a microscope you can actually see them.
Once exposed to liquid (usually your saliva), the candy breaks down and the carbon dioxide is released, resulting in that sizzling feeling. So yes, if you expose the candy to any sort of liquid, it will pop. But contrary to the urban legend, mixing Pop Rocks and Coke won’t result in an explosion.