The other day, I had been driving for about an hour and whilst stopped at some traffic lights, I pumped the brake pedal about 15-20 times, out of boredom.
I then noticed that the pedal become very spongy and ended up going all the way to the floor. Braking was difficult, but I was able to still stop the car. I tested braking hard as well, the ABS did kick in. Just the pedal was "slow and spongy", going to the floor after the brakes "grabbed".
The following day, I took the car for a test drive in the morning, the brake pedal was back to normal and was not spongy anymore, felt quite firm.
What could this be? Does it just need a bleed? The brake fluid level is at max.