As far as I know I haven't used Ajax anywhere in my code. Yet, while debugging, I have breakpoints being hit with 'admin-ajax.php' at the root of the call stack. This second hit of my breakpoint occurs between 10 and 30 seconds after the original. The weird thing is, as of yet there is no HTML output, so no scripts are present in the browser.
Any ideas why or where this is happening and why my php scripts are being called twice?