Can human blood boil in outer space?
Any liquid has a direct relationship to ambient pressure. The higher the pressure, the higher the boiling point, and vice versa.
📌 The problem is that while a liquid boil in space, blood will not. Fluids like saliva in the mouth will boil.
However, blood, unlike saliva, is in a closed system, and your veins will hold it under pressure in a liquid state. Even if you are in a complete vacuum, the fact that the blood is closed in the system means that it won't turn into gas and escape.