Not so. Your skin is actually more than strong enough to prevent your blood from boiling. And without an atmosphere, radiative cooling is really slow. Exposure to vacuum (or just really low atmospheric pressure) kills you by anoxia after a couple of minutes; less than a minutes of exposure tends to do no lasting damage, unless you try to hold your breath and end up rupturing alveoli.
After about ten seconds a victim will experience loss of vision and impaired judgement, and the cooling effect of evaporation will lower the temperature in the victim's mouth and nose to near-freezing. Unconsciousness and convulsions would follow several seconds later, and a blue discoloration of the skin called cyanosis would become evident.
At this point the victim would be floating in a blue, bloated, unresponsive stupor, but their brain would remain undamaged and their heart would continue to beat. If pressurized oxygen is administered within about one and a half minutes, a person in such a state is likely make a complete recovery with only minor injuries, though the hypoxia-induced blindness may not pass for some time. Without intervention in those first ninety seconds, the blood pressure would fall sufficiently that the blood itself would begin to boil, and the heart would stop beating. There are no recorded instances of successful resuscitation beyond that threshold.
