That's why I just middle click to open everything on a new tab nowadays. Back button still works 90% of the times, but when it's hijacked it's incredibly annoying, and I have plenty of monitor width for the tabs.
Longpress on iOS Safari gives you a menu that lets you open a link in the background, which is essentially open in a new tab. I use it all the time, e.g to work through the HN front page selecting some comment pages to read later
I wish I could say thanks, but when I tried it out just now, I realised that I have seen it many times — trouble is, it's labelled in my mind as "that annoying popup I keep triggering by accident, how do I disable it?"
Still, have a metaphorical cookie: even though I don't like the thing, sharing knowledge kindly is always good :)
If nothing else, now you know what behavior was triggering the thing you don't like. Maybe now you can start to make it only happen deliberately, which might make it less annoying.