It also stores the last position. So if you have one of these two monitor setups at home with your laptop and you have a window on the second monitor, then you take your laptop on the road without the second monitor, you can make yourself rip all your hair out trying to find the missing window.
Alternatively, switch to Firefox or Opera
Mozilla on Windows exhibits similar behaviour to that reported by planemad2. One should have an open mind wrt to software.