The chemists say that sucrose technically doesn't have a melting point.
However, at 366.8 degrees (F) it inverts, which means it separates into glucose and fructose.
Now, here's where things get messy, literally.
The melting point of glucose is 294.8 degrees (F) and the melting point of fructose is 217.4 (F), so by the time sucrose inverts, your pan is well above the point at which either glucose or fructose do melt.
So, low and slow is the way to partially caramelize, AKA toast, sucrose.
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