Abstract: Mpemba effect is about faster freezing of a hotter sample of water, than a colder one, when quenched to a fixed subzero temperature. This fact had found mention in the writings of Aristotle and was rediscovered in the last century by Erasto Mpemba. Recently there are efforts to discover similar effects in systems and phase transitions of other types. However, the observation in water still remains a puzzle. In this talk I will show results from computer simulations demonstrating the existence of the effect in a model water. I will also present results from other model systems that, unlike water, do not encounter metastability during phase transitions. A qualitative discussion on the differences in the reasons between the two varieties will be provided.