I'd also like to know how to turn this 'feature' off as it's causing complaints by our analysts since moving from 7.3 to 7.5.
Short of removing the attribute (incident description) from the specific query (however it's on our query for a reason) I'm at a loss.
I'm afraid there isn't a way to switch it off entirely. Here is an enhancement request that you can vote on if you want to: Control of Tooltips in Queries
I would suggest considering putting large multiline text attributes onto the preview section of the query so they are only shown when that record is highlighted. You can also scroll to see the full details of the text within here. This is really what the preview section is for and the summary/title is a shotrer field to be shown on the query list.