I’ve always wondered since I was a kid why it does this.
[This image is representative of what I’m talking about](https://i.pinimg.com/474x/66/68/d6/6668d6e7d6cc10177eb2196c84a822d6–sweet-tea-making-memories.jpg)
This happens with anyliquid. You put air in it the bubbles will rise to the surface and usually pop, but milk has a lot of other additives besides water that makes it thicker so the air has trouble rising to the surface
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