Playing v1.11, as Russia. Started in 1900, carefully increased the fleet, allied to the UK and defeated Germany, taking the German NE Pacific territories. Again built up the fleet to a second conflict with Germany, and was removed from office. After that, I was given a sea battle, where 2 German BBs were sunk, and I gained 2 prestige points. End of game.
I would have expected that the game would end directly, though I did wonder if I was being given one last chance!
Battles are processed dead last in the interturn sequence, so I'm not surprised to hear of this happening, though, yes it does seem a bit odd.
But in real world terms, think of it as you being given your two weeks notice, and a fleet engagement happening in that time. Or your successor is still settling into office, and plans that you set in motion end in a fleet engagement. Because really, you're playing two different admirals in RTW: Jackie Fisher for 30 days a month, and John Jellicoe on the 31st, if you take my meaning. And it's "Fisher" that gets sacked (and historically, actually did get sacked).