Answer: Pop Rocks

In 1957, General Mills research chemist William A. Mitchell patented a novel way of making candy that created a new taste and mouth feel hitherto unseen in the confectionery world: candy infused with carbon dioxide that “popped” in your mouth.

The concept would languish on the shelf at General Mills for decades until they released the candy to the public in 1975. Despite the novelty of the candy, the product failed to take hold. Sales were discontinued in 1983 due to poor sales and poor shelf life (early Pop Rocks would often be “flat”, as it were, by the time the consumer opened the package). Eventually General Mills outsourced the creation and distribution of the product and Pop Rocks grew in popularity. Now both the original Pop Rocks candy as well as numerous varieties made by companies outside the U.S. ensure carbonation-infused candy is widely available.

But how exactly does the tingles-on-your-tongue gas get inside the candy? The candy is prepared in a fairly traditional way by melting sugar, mixing in colorants and flavors, but then rather than allowing it to cool immediately, the hot mixture is exposed to a carbon dioxide gas at 40 bar of pressure (roughly 600 pounds per square inch) which forces the carbon dioxide gas into the still soft candy. When the candy cools the gas is trapped inside the now hardened sugar and only released when the candy is consumed.