If someone told you that a container of hot water would freeze quicker than a similar container of cold water put side-by-side in a freezer, would you believe them? Surely, you would argue, the hotter water has to cool down to the temperature of the cooler water before it freezes, so it must take longer. But you would be wrong. In practice it works the other way round, which, for most of us, is completely counter-intuitive. If, like most testers, you want to see evidence to support this claim, then look up the ‘Mpemba Effect’ and you will see that this phenomenon has been documented since the time of Aristotle, circa 350BC.