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.
This ticket has been marked as a duplicate of MC-24850, in favor of the better description/information provided.