On a totally unrelated, yet totally awesome, matter, I had my first real life experience with supercooled water the other day. I had seen videos of water well below 0C not frozen, but hadn't ever witnessed it. Then last week I was in my lab preparing some reagents. I put a salt solution in the freezer to cool it, and when I came back a couple hours later it was still liquid. Confused, as it seemed really cold, I picked the container up to inspect its temp. Immediately upon touching the container (and thus disturbing the supercooled liquid within) it turned solid. Within probably one second this 500mL bottle of solution went from totally liquid to totally solid. It really was an amazing thing to see first hand when not expecting it (if you're a science nerd). But anyway, I guess my point (I don't really have one, but I'm going to make one just to be somewhat relevant here) is that even phase diagrams can be incorrect in the perfect circumstance.