Will he explode if an astronaut takes out his spacesuit?

If an astronaut takes off his or her spacesuit while outside the pressurized climate of the spacecraft, they will not instantly explode. They will however, not be able to breathe because there is not enough oxygen for them outside of the earth's atmosphere. They will also freeze without the temperature regulation necessary.

If left outside of the space for more than a few minutes, the astronaut would die. If the astronaut gets completely disconnected from the ship and starts floating through space, he or she may eventually run into space debris, or a black hole, or burn up if they come into contact with the earth's atmosphere or the atmosphere of another planet.