Sounds like you experienced female ejaculation. All women can do it, just many of us have never experienced it first hand.
Women can have 2 different "types" of orgasm. Orgasms from clitoral stimulation feel entirely different to those from G-Spot stimulation (which is what you experienced.)
Its a lot more difficult to have a g-spot orgasm, so kudos for that! Lol. But yes, what you experienced was entirely normal; and pretty mind blowing I should expect. Relax about it, and point out to your bf how difficult it is to make a girl do that (most guys have trouble!) relax and have fun with it. It really is no big deal
