As far as enamel paint and baking, it does make the paint cure faster. However, what you end up with is not baked enamel. The term baked enamel is used when talking about the baked ceramic (or porcelain) finish used on appliances and bathtubs.
As far as the water treatment goes, it does work... Enamel dries by solvent evaporation and cures by oxidation (or cross-linking if a hardener is used). Water speeds oxidation. Just like with iron and rust.
Heating the enamel helps dry the solvents and speeds the reaction time for curing. In some cases, if the humidity was too high when the paint was applied, or if it was applied too thickly, it may be weeks to get full cure. This is because the outer layer of paint is cured, but inside it's sealed off from the air. Solvents can't get out and oxygen can't get in. B
Baking can help with this sometimes by allowing the solvents inside to escape... Why? The vapor pressure of the solvents is increased at high temperatures and the outer layer softens and the solvents can get out.
Baking works well, but don't rush it. Heating the curing paint too soon can cause bubbling (solvent pop), loss of gloss, smoothness issues, etc.
John