- Visit https://badssl.com/
- Click on the "expired" button under "Certificate" (on the left).
- Get an SSL error page
- Click back button in browser UI
- Note you are on the "start page" or a new tab page, not the predecessor page (https://badssl.com homepage).
Looks like the page with certificate error isn't being added to the back "stack", but when back is pressed, the browser recurses up a step, and ends up back at the root (new tab), since hitting forward from that page then takes you to the main badssl page (as pressing back in the first place should have done).