Water Boils or bubbles what do they suggest?

[Snake2715]

So I have a question on this.

I over the last weekend hooked into a larger musky at least 3ft long and possibly a bit more. I posted about it in another thread.

I have since returned to the spot and fished for him. Now the question is the day I hooked up (07/25) I noticed bubbles or boils come to the top of the surface. When I noticed the bubbles it was shortly before I caught the musky... I mean within seconds. I mentally figured he was turning to catch my jig and on the next cast I hooked up.

Then Monday 07/28 I noticed a small set of bubbles come up in the same pattern, it was shortly after I thought I had a bit on the jig (I am new to fishing a jig).

Nothing ever turned up on Monday. But the question is haunting me. Does this signify movement of a potentially larger fish at or near the bottom?

When I was little I was always told it might be a carp or turtle moving around down on the bottom.

Anyone have their opinions or thoughts?