I've put a video of this occurring on Youtube (because the video file is too big to upload here!)

https://youtu.be/0N3bf0wxzlU

Briefly though, when you have a water column with soul sand at the bottom and you use dispensers with buckets to suck the water blocks back in, the bubble effect remains in the air (and continues to function as before).

Before triggering dispensers:

And after:

Resulting in a column of rogue bubbles: