interactive debugging with tinker?

I read that the underlying PsySh is capable of interactive debugging, but after much googling I did not find any example of how to debug a laravel web app running on apache (MAMP). If I add eval(\Psy\sh())) in my code the browser just stops, keeps on loading the page and never ends, but where do I see the shell prompt? Does anybody use this for debugging? Seems to be really cool....