I think you are wrong.
Solubility mainly depands on the balance of intermolecular force between solvent and solute.
Simple molecular structure's molecules NOT always have high solubility in water. (eg C6H6) If the intermolecular force between solvent is lager than solute's , the solubility is low.
The reason for high solubility of sugar(sucrose) is that it has lots of
-OH bond in its structure and it is polarized. So its intermolecular force is simular to water's.
Also, ionic compounds often have high soluility because the polar solvent H2O can ionize ionic compounds.(But for OH- / O2- , usaually not)
PS. Who says higher tem, higher soluility?? It seems wrong. (consider Ca(OH)2 )
Sorry for poor english and 有錯請指正.
