On the boil
Definition 1 of 2
Pro Tip 1/3Attention Needed
Use to imply ongoing effort and focus on a task or issue. 
We must keep the negotiations on the boil, or we risk losing the deal.
Pro Tip 2/3Continuous Action
Suggests actions are continuing to ensure progress doesn't stall. 
The team is setting nightly rehearsals on the boil to prepare for opening night.
Pro Tip 3/3Active Progress
Indicates something is moving forward and hasn't been completed yet. 
Our restaurant plan is still on the boil; we're finalizing the menu.