Random events can occur at any time and may be a boon or a curse, depending on your luck and your situation. While such events aren't going to totally destroy your empire, the wrong event at the wrong time might be truly disastrous if an opponent realizes the opportunity in time. Thankfully, enemies aren't told of such events... unless spies tell them. (Also, game creators have the option of turning off or otherwise adjusting the rate of random events.)
The following 3 pages are in this category, out of 3 total.