The carbon dioxide contained in pop rocks is heated and vaporized in the mouth to generate thrust, which makes pop rocks particles jump in the mouth. Someone has done experiments. They put pop rocks into the water and observed that bubbles kept popping up on its surface. It is these bubbles that make people feel "jumping". Of course, this may be just one reason.

Precautions and key points of pop rocks:

When making pop rocks, high-pressure carbon dioxide gas should be added to hot syrup. Carbon dioxide gas will form tiny high-pressure bubbles in sugar. When the pressure is released after the candy is cooled, the candy will break, but the fragments still contain high-pressure bubbles, which can be seen through a magnifying glass. When you put sugar in your mouth and the gas is released after the sugar melts, you will hear a "pop" sound.

What you hear and feel is actually the process of releasing carbon dioxide gas from each bubble, which feels like fudge jumping in your mouth. Because the syrup is cooled and solidified under high pressure, and then it returns to normal pressure. After decompression, the candy filled with high-pressure gas will crack, and there will still be many small bubble structures to seal the high-pressure gas in the debris.

Refer to the above content: Baidu Encyclopedia-Pop Rock