Ok, so in my gen chem 1 class, the teacher showed us that ethanol would not dissolve a sugar cube while water dissolves a sugar cube easily. No explanation was given, she just told us we would find out in gen chem 2. Here i am in gen chem 2, and the same thing is shown to us asking for an explanation. Again, nothing is explained to us.

when i look at it on the molecular level, sugar is C6H12O6 while water is H2O. I see a minor corellation involving the ratio of hydrogen to oxygen with sugar and water (2 to 1 with both), but that's all i can think of. The formula for ethanol: C3H5O3

Like dissolves like. Sugar contains several OH groups that are polar. H2O molecules (HOH) are polar. Polar solvents dissolve polar solutes. This rule is not in concrete but it works in general.