Slitherine

Sometimes when a city is at it's maximum population and I sell or distribute slaves, a building I am working on or have completed will disappear, at least it seems to.
Is this happening because the population can no longer support all those buildings? How does this work?

A building might be destroyed if you are not producing enough infrastructure compared to the upkeep needs, it should be mentioned in the log. Other causes might be a raid.

OK, thanks. I don't think it was a raid and it could have been the infrastructure issue, but I guess my real question remains. If you have a city with, for example, 20 people and it has 20 buildings, if you remove people by selling or moving slaves from that city, will the game then remove buildings to compensate or remove a building which is in progress? It's not a question of "did it happen" but rather "can this happen".

No, buildings are not removed if you have not enough population (providing building slots), rest assured.