Scale formation, due to the presence of dissolved salts and organic impurities, poses serious problems in several practical applications, ranging from household utensils to industrial boilers, and affects industries including desalination, oil and gas, and cooling towers. In particular, salts with inverse solubility with temperature have the tendency to crystallize and adhere to the heat transfer surface and adversely affect the thermal and fluid transport. In the present study, we investigate the mechanism of salt crystallization during pool boiling. The boiling performance parameters, such as, heat transfer coefficient and critical heat flux (CHF) are examined for an undersaturated solution of calcium sulfate. Simultaneous high speed and infrared imaging enables determination of the interdependence between crystallization and bubble dynamics, including, bubble nucleation, growth, and departure. The effect of the three phase contact line during bubble evolution on the crystallization-induced scale formation is demonstrated.