Why should an ionic solute be INSOLUBLE in water?
Well, clearly, the force of attraction between anion and cation IS GREATER than the interaction between solvent and the solvated ion....
And if we look at aqueous solubility, carbonates, phosphates, sulfides, and oxides, whatever the cation, TEND to be insoluble in water. And why? Because for these anions, which have a greater than unit charge, necessarily have a greater degree of electrostatic interaction, which can be clearly appreciate from
Of course, aqueous solubility is an experimental phenomenon...