Chemistry today is easy. The concept of solubility products already taught in school by Mr lau.
The solubility product refers to the Ksp which is the product of ions raised to it’s stoichiometric coefficient. From Ksp, one can determine the solubility of a substance which is the amount/ no. of moles that can be dissolved in solution before forming precipitate.
When the Qsp which is the solubility product at any given concentration of ions is more than the Ksp, there are more ions in the solution, equilibrium position will shift to the left, thus forming precipitate. vice versa.
When an common ion is added to the solution, the solubility of the salt is lowered.
Besides that, solubility greatly increases if ions can form complex ions.