Nether Portal makes glass breaking sound when deactivated with water

What I expected to happen was...:
The Nether portal makes no sound or a proper sound when deactivated with water.

What actually happened was...:
The portal makes the glass breaking sound.

Steps to Reproduce:
1. Have a working Nether portal.
2. Pour water (or lava) into it.
3. The portal deactivates making the glass breaking sound.