why is the application I'm using go to the background every 50 seconds?

Every 50ish seconds I need to re-click on the application I'm using in order to keep typing--for example, as I was typing this out, the cursor disappeared, the application screen color shifted slightly and I had to click here again to continue. This happens every 50 seconds no matter what. It's like another application is trying to startup in the background or something but I can't actually detect anything going on. If anybody knows how I can diagnose this that'd be great. thanks. (This is on a late 2012 iMac running Sierra).