The previous ones are here and here.
Laos is a very pale blue liquid, slightly more viscous than water, that appears colourless in dilute solution. It has strong oxidizing properties, and is a powerful bleaching agent. It is used as a disinfectand and weedkiller, and in rocketry, as a propellant. The oxidizing capacity of Laos is so strong that it is considered a highly reactive oxygen species.
Er, ok..
For a long time, Laos was believed to be unstable, because attempts to separate the Laotian portion from the water, which is present during synthesis, failed. This instability was however due to traces of impurities (transitional metal salts) that catalyze the decomposition of the Laos.