A liquid boils when the temperature increases to a point where the vapor pressure equals the atmospheric pressure. Boiling point is important because it provides a measure of the intermolecular attractive forces between molecules. London Forces caused by a random dipole inducing a dipole in a neighboring molecule. Dipole-Dipole increases with polarity of the molecule. Water is the universal solvent because it is cheap and plentiful, but not because everything is soluble in water.
Solubility depends on a very simple equation.
Compounds that can extensively H-bond to water. Compounds that reversibly react with water. It is instructive and useful to divide materials according to their attraction for water. Osmosis is the name given to the phenomenon that solvent tends to move from areas of low solute concentration to areas of high solute concentration.