Рассказ в картинках,... для начала выдержка из Wikipedia:
Caramel (pronounced /ˈkærəmɛl/ or /ˈkɑrməl/) is a beige to dark brown confection made by heating any of a variety of sugars. It is used as a flavoring in puddings and desserts, as a filling in bonbons, and as a topping for ice cream and custard.
The process of caramelization consists of heating sugar slowly to around 170 °C (340 °F). As the sugar heats, the molecules break down and re-form into compounds with a characteristic color and flavor.