Where I understand you are trying to maximize your revenue… Those ads are annoying as hell and I am sure you will start seeing a drop in people posting. Less people posting or posting less means the rest of the page ads will be seen less.
Just my .02. 
Can you show an example? Google Ads recently increased the frequency of full page pop ups and its breaking a lot of sites around the internet (we don’t have direct control over ad display)
That makes sense. Gotta love google. LOL!
It’s a modal window that pops center screen. It did not do it when I pulled this page or I would have screen capped it.
Maybe Google has a glitch, who knows. I have had that happen on my site… I disabled google ads. LOL.
We don’t server pop up ads as far as I know. I’d be really interested to see a screenshot of that.
I closed and reopened my browser. I got another. Here is a screen cap.
It could be as Joseph said… Google may have changed something or a Google glitch. They do have an option to serve pop-ups
Gotta love Google. 
Glad I could help. 
I have disabled them.