Water is just mundane and seems well-understood in many respects. However, there are still quite a lot of things that motivate people to find more. For example, how water molecules arrange themselves when they adsorbed on an adsorbate. Another instance is, I think more associated with the thermodynamics of water: it has been claimed that, hot water cools faster than cold water when they are placed in the same chamber. This was named after its discoverer, a middle school student Mpemba. There came a latest study on this [http://arxiv.org/ftp/arxiv/papers/1101/1101.2684.pdf]:
In this paper we have presented data confirming that water initially at higher temperature cools at a faster rate than water initially at a lower temperature and that this trend continues past the point at which the two samples reach the same temperature: the crossover temperature. Furthermore, our data indicates that the starting temperature affects the crossover temperature in a reproducible manner. We have confirmed that warmer water indeed cools faster than colder water and that, surprisingly, this trend continues past the point where the temperatures of the two samples are the same. Our results show that when using optimal initial temperature conditions, the crossover temperature is found to be 2.7 oC whereas our other set of initial conditions gave a crossover temperature of -0.07 oC. These data taken together provide a definite quantitative evidence of the Mpemba effect.
