that is quite simple actually.
Butter and skimmed milk also come from the same source. You have a complex mixture of stuff that is differently viscose, so in mixture it all ends up with a certain viscosity. Now you separate it and you get stuff that is almost solid and you get stuff, that is very liquid, or in the case of crude oil you get some gaseous fractions.
But not if the pressure is mostly coming from the external. Or worse if we look at Egypt, where now an even worse dictator than Mubarak rules, after the Egyptians have elected people the West didn’t like, and getting couped quickly.