What does heat do to sugar?
The effect which heat has on Sugar depends on how high the temperature is, and the duration of exposure, and whether an oxidizing gas [air for example] or an inert gas [or no atmosphere] is present: * At low heat, generally nothing happens. * At a somewhat higher heat, the Sugar can melt. * At more heat the Sugar can be scorched [called "caramalizing"]. * At greater heat, IF an oxidizing atmosphere is present, the the Sugar can ignite and burn. * If the sugar is heated to a high temperature in an inert atmosphere [as in an evacuated retort] then the sugar can be broken down into a combustible gas, but will not burn due the absense of any oxidizer. This process is called "Pyrolysis."