Many solvents such as diethyl ether are considered time sensitive. Over time, they react with oxygen in the air to form explosive peroxides. These often have a crystalline appearance and can be extremely shock sensitive. The bottle should not be moved or, if it has been picked up, moved carefully to a safe location. A licenced explosives company should then be contracted to safely remove it. If you consider there to be an immediate risk to people in the area, ordinance disposal can be called. If the bottle was correctly labelled you could also look up its properties as some solvents have freezing points close to room temperature.
Charles Harrison is a safety advisor at a UK university