Explosive decompression is a violent, sudden drop in ambient air pressure that occurs within one tenth of a second.
Disabling (or the failure of) the containment field around the shuttlebays or cargo bays or a major hull breach on board a starship in space (or any environment of substantially lower pressure) will result in an explosive decompression. (TNG: "Contagion", "Disaster")
Opening the shuttlebay or cargo bay hatch without the containment field will also have the same result - on a Galaxy-class starship, decompressing the main shuttlebay causes a reaction sufficient to move the ship slightly. (TNG: "Cause and Effect")
In 2259, Montgomery Scott opened an airlock aboard the USS Vengeance to allow access for James T. Kirk and Khan Noonien Singh. A Section 31 security officer was blown into space as a result. (Star Trek Into Darkness)
One of Dukat's duties, when he was a Glinn serving aboard the Cardassian starship Kornaire, was to clean out a compartment where three men had been killed by explosive decompression. In 2374, he would tell Benjamin Sisko that "I didn't sleep for a week after that". (DS9: "Waltz")
During the Battle of the Bassen Rift, the Reman warbird Scimitar launched a volley of photon torpedoes at the USS Enterprise-E's bridge, resulting in an explosive decompression which killed Lieutenant Branson. (Star Trek Nemesis)