How Gas Gets Inside the Candy
Pop Rocks begin as hot sugar syrup. While the syrup is under pressure, carbon dioxide is mixed into it. As the candy cools and hardens, the gas remains trapped in tiny pockets throughout the sugar. Breaking the solid candy into pieces leaves those pockets sealed inside—rather like miniature bubbles held in a rigid shell.
Why It Pops in Your Mouth
Saliva dissolves the sugar around the pockets. Once that barrier gives way, the compressed carbon dioxide rushes out, making small fractures and vibrations in the candy. Those quick releases are what you hear and feel as crackling.
The effect is not a separate ingredient reacting or the candy burning. It is gas escaping from a dissolving solid. Each little pocket releases at a different moment, so the sound comes in a series of tiny pops rather than one burst.
