The answer to this is so simple. If you have a tab open, it is likely because you have clicked on another tab. The tab you have clicked on has closed itself. But if you click on another tab, a new tab opens and all your previous ones close. This is a common problem and happens to us all the time.
I am the type of person who will organize my entire home (including closets) based on what I need for vacation. Making sure that all vital supplies are in one place, even if it means putting them into a carry-on and checking out early from work so as not to miss any flights!