Let me introduce you to the concept of vapor pressure. The volatility of a material depends on the temperature. Even cold water will still evaporate slowly. Instead is being a binary things, the vapor pressure will increase gradually as the temperature increases.

This means, that you can empty a glass of water by just waiting. You don’t even need to boil the water to make it evaporate. It’s already evaporating very slowly, even in room temperature.

Therefore, raw milk straight from the udder, is also evaporated milk.