If butter is in fact an emulsion of fat and water (and i am too lazy to confirm that), it should be boiling (or starting to anyway) at below 100 rather than above. Yes proteins and the like dissolved in water may elevate the boiling point but the fact that you've got a two immiscible liquids creating an immiscible vapors will have higher effect. Ochem 101, immiscible vapors have additive vapor pressures (not proportional to their mol fraction) since they are additive, having even a drop of one of the liquids will make it easier for the mixture of vapors to reach 1 atm and thus boil. In short, steam distillation.