tripod
鬲 centers on an ancient three-legged cooking vessel: a tripod. Its meaning is concrete and specific to this type of container.
鬲 is a pictograph of an ancient tripod cooking vessel with three hollow legs. The modern form retains the general shape of the vessel.
The top part looks like a wide opening, and the lower strokes suggest three legs. Picture an ancient bronze tripod used for cooking: 鬲 is that tripod.
For カク, imagine a tripod with a *crack* in one leg: crack -> カク, and the tripod wobbles.