Next time you're at the beach, have a care: Out on the ocean quantum mechanics has found way to invade our everyday world.
There's a whole species of gigantic, rouge, waves out there. They can hide 'beneath' smaller waves, manifest themselves, and vanish again. And they don't have sloping sides like regular waves - these are sheer walls of water, breaking even as the grow to massive size.
They're a non-linear wave, governed by the equations of quantum mechanics. Which means it can ignore all the normal rules of waves.
Why do they happen? It's literally quantum mechanics manifesting in the macro scale world....