This could (kind of) explain the thirstiness a lot of us have experienced.
One comment on that page mentions retaining water when you're dehydrated, and I know from experience this is true. I will retain a lot of water, regardless of temperature, time of the month, etc., if I get dehydrated for more than a day. I get rid of the water retention by drinking lots of water.
I wonder if what's happening (keep in mind I'm not a real scientist and I'm pretty much guessing) is the water retention from filling the fat cells sets off a dehydration-like response, where your body misinterprets the fat loss as a type of water loss, somehow, or maybe the water moving into the fat cells depletes other parts of water, setting off a thirst signal. We end up drinking lots of water to satisfy the thirst signal, the body realizes lots of water is coming in either to replace the lost water from the depleted areas or to cover the "fake" water/fat confusion, lets go of the retained water in the cells, and we have a "whoosh" of weight loss.
It could explain Karky's observations about how she has a noticeable loss each time she gets really thirsty and drinks a lot of water.