science 101 :
There are a lot of misconceptions about decompression (mostly from Hollywood). The eyes would certainly not bulge out, since they're secured too firmly in place. The walls of large blood vessels are too sturdy to rupture. Also, there isn't enough expandable tissue within the body to make it bloat out and explode.
To put it in perspective, lets say a spacesuit is pressurized at 1atm of pressure. Vacuum would, of course, be 0atm. That would mean a difference of just 1atm of pressure. When a diver descends to 33 feet underwater, he is at 2atm of pressure. If a diver descends to 33 feet and spends a while there (his body acclimates to the pressure), then ascends rapidly, then he would experience the same pressure drop as an astronaut removing his helmet... it happens frequently, but we've never seen a diver explode. If the human body were that expandable/compressible, then it would be impossible to dive less than a few feet underwater.
If an astronaut were to take his helmet off, the first effect would probably be the rupture of the tiny delicate blood vessels in the eyes.
The next step would depend on whether or not the astronaut had taken a deep breath beforehand. If he had, then he would have a small store of oxygen in his lungs, so he would remain conscious for maybe a few minutes, but would probably suffer lung damage from the pressure difference. If he hadn't taken a breath he would lose consciousness very quickly, maybe 15 seconds.
In the meantime, gas bubbles would form in his bloodstream from the drop in pressure (the same thing happens to deep-sea divers if they swim to the surface too quickly), which could lead to heart attack or stroke... though the astronaut would probably die before that point.
The liquid on his tongue and lips would quickly boil in the vacuum, but this would not be hot, it would produce evaporative cooling, forming frost on his lips the way frost forms on a can of compressed air while being used.
The astronaut would eventually freeze (in shadow), but it would take a few hours to days, depending on the insulation in the suit. On earth, body heat can be whisked away by conduction into water or air, but in space, heat can only be radiated away, which is a slower process. On the other hand, if he were in direct sunlight, he'd get burned very quickly since there would be nothing to filter out the sun's rays.
A few humans have actually been exposed to vacuum. Back in the day, there was an engineer at NASA testing out a space suit in a vacuum chamber. His space suit leaked and he was exposed to almost total vacuum for 15 seconds. He lost consciousness, but luckily, they were able to repressurize the chamber in time, and he made a full recovery (i.e. his head didn't explode, or anything like that). Also, a man who tested high-altitude balloon jumps lost pressure in his glove, causing his hand to swell to twice the normal size. After returning to earth and recovering, his hand was fine.
