My boss just texted me implying that I will be fired if I go on vacation for four days, even though I gave two months' advance notice. My family already purchased the tickets and everything. Is there anything I can do?

There’s a difference between giving two months’ notice for a planned absence and getting permission. There needs to be enough cover in place, and if other employees have already booked leave for that week then there may not be enough people to cover your shift too. If your boss accepted your leave proposal at the time then you have a case for unfair dismissal regardless of whether your boss wanted to change it, and they should have taken time to consider the request before granting you leave. But if the ball swings the other way and your boss didn’t agree to the absence, then it might be an excuse for them to get rid of you. Check your employment contract to see what the procedure is. It really is down to which party defected from the agreement, and if you can find fault with your employer then maybe you should consider working for a better one (after you’ve sued them for damages of course).