Your title sounds like my experience .. fast and spontaneous! I woke up about 3 am with minor cramps thinking I need to poop (because I had that feeling the night before). Stand up and feel things get a bit wet but don’t think much of it. Go to the bathroom.. but number 2 doesn’t happen. Go back to bed.. cramps get slightly worse and I feel things get a bit wet again. I call my midwife around 3:30am and she said to take a shower and come in. Before I hang up the phone, I stand up and sploooosh, my water breaks. On the way, the pain starts to get worse. We get to the hospital and could I barely hold it together while being registered. Get to a room around 4:49am and find out I’m fully dilated. Pain becomes unbearable. They told me not to push but I couldn’t help it with each contraction. Little one pops out at 5:01am lol.