What do kicks feel like at 21 weeks?

So I’m a first time mom and this is the first time I’ve felt like I have actually experienced a kick but I’m not sure. I just wanted to know if this sounds like a kick to those who know how it feels.

It’s like at the bottom/lower part of my bump and it felt like a little “bump” or like a bubble popped kind of and it make me jump a little. But I only felt it once last night and I feel like I’ve been feeling it this morning but I don’t know how often is normal to feel it. Does this sound like gas or baby?