The tags in the dribble post say it all: after effects / cell animation / frame by frame. Also the link in the page points to the page where you can buy the animation, where it says (emphasis mine):
Carefully crafted frame-by-frame animations are at the core of Colloid. Each character is formed from a dance between two colored liquids. The hand-drawn motion has tons of detail, like tiny drops with lifelike movement.
As commented by Joonas you can find tutorials such as this and this one on the web. In the videos the author actually uses a combination of manually redrawing the shape every few frames + motion along a path + extra deformation to make the blob look more organic.