A few days ago, Jason Asselin of upper Michigan looked up at the sky and saw THIS. Thankfully, he had his camera.
Though it looks like the world is coming to an end, it's not a catastrophic atmospheric collapse, nor even an indication of severe weather for that matter. They're called mammatus clouds, and they form when air sinks, unlike other clouds that form due to rising air. This causes pouches of condensation to form, which is what gives these cloud a kind of bubbly and bumpy appearance.