Safari memory usage out of control

What in the out of control memory usage is happening here?

Recently I've been getting the "Force Quit Applications" popup happening while using Safari. It is claiming that Safari is using 44GB of memory. But when I look at Activity Monitor, it is not using anywhere near that amount (this is just a lowly MacBook Air with 8GB).

Any idea what is happening? And more importantly, how to solve it? It's getting quite frustrating since I typically can't have more than a couple tabs open before this starts occurring.