Bounce rate vs organic rankings

Here's why I think bounce rate is a ranking factor.

I've conducted this test (accidentally) several times in my career.

1. Deploy an aggressive pop-up 1 second after your visitor lands on the page

1a. Observe a massive increase in bounce rate in GA

1. Watch organic traffic begin to decrease day over day and week over week

2. Reduce aggressiveness of pop-up (e.g. after 120 seconds)

3. Watch organic traffic begin to rise again

Any other theories if not bounce rate?