Manufacturing
The candy is made by mixing its ingredients and heating them until they melt into a syrup, then exposing the mixture to pressurized carbon dioxide gas (about 600 pounds per square inch or 40 bar) and allowing it to cool. The process causes tiny high-pressure bubbles to be trapped inside the candy. When placed in the mouth, coming into contact with saliva the candy breaks and dissolves, releasing the carbon dioxide from the bubbles, resulting in a popping and sizzling sound and leaving a slight tingling sensation. The bubbles in the candy pieces can be viewed when aided by a microscope.
Read more about this topic: Pop Rocks