Once it cools you release the pressure and the candy shatters, but the pieces still contain the high-pressure bubbles (look at a piece with a magnifying glass to see the bubbles). 

When you put the candy in your mouth, it melts (just like hard candy) and releases the bubbles with a loud POP! 

 When the candy hits the saliva in your mouth, it quickly dissolves the thin barriers containing the pressurized carbon dioxide.  

This results in the bubbles bursting fairly quickly, releasing the trapped carbon dioxide, often with sufficient force to cause the candy to pop and sometimes jump in your mouth.

sell 10 in a package.

Sugar, lactose (milk sugar), corn syrup, andflavoring

Malaysia