user14688: I saw this cool effect that blends bubbles into each other, and the space that they are overlapping is transparent.

How can I achieve this effect in after effects?

user11523: You are interested in blending mode "Difference"
You can use it in "Blending mode" of layer, or on masks.
UPD: Adding screenshot, as asked

Red — Mask Blending
Blue — Layer Blending

14688: <p>I saw this cool effect that blends bubbles into each other, and the space that they are overlapping is transparent.<br>
<a href="https://i.stack.imgur.com/BVtGI.gif" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/BVtGI.gif" alt="enter image description here"></a></p>

<p>How can I achieve this effect in after effects?</p>
 11523: <p>You are interested in blending mode "Difference"</p>

<p>You can use it in "Blending mode" of layer, or on masks.</p>

<p><strong>UPD:</strong> Adding screenshot, as asked
<a href="https://i.stack.imgur.com/JFMUS.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/JFMUS.jpg" alt="enter image description here"></a></p>

<p>Red — Mask Blending</p>

<p>Blue — Layer Blending</p>
