say i add NaOH dropwise into a solution containing Aluminium ions. The Aluminium ions bond with the hydroxide ions to form a white insoluble salt Al(OH)3

I then add NaOH in excess and the insoluble aluminium salt dissolves??? Why tf does this happen and why would the quantity of NaOH added change whether the salt is dissolved, shouldnt it just make more Al(OH)3 until the aluminium ions run out?