Fun and interesting read from Smithsonian Mag:
he sent away for bottles of soda and plunged them into the frosty depths of his freezer to chill for his thirsty customers. When he popped the lids, the sodas instantly turned slushy, says Phil Knedlik, one of Omar’s two sons.
Though it sounds like a party trick, this actually involves some flashy chemistry. There are likely a few factors at work here, but one of the most important is the formation of what is known as a supercooled liquid. This means, that the drink is actually colder than the point at which the solution transforms into ice—but not frozen yet.
This can happen because for ice to form, it needs somewhere to start—a rough spot in the glass or even a flake of dust. Without it, the water just keeps chilling. When you open a bottle of supercooled soda, the bubbles of carbon dioxide begin to fizzle out, providing plenty of surfaces for ice to form, creating a refreshingly light and slushy beverage. Try it for yourself.