I was sent to another country overseas for (initially) one month (they made it two in the end, deciding for it a day before I was coming back). They noticed me about it one week before the depart.

While I was abroad, working my ass 14 hours a day, 6-7 days a week, I was contacted by a headhunter. I explained them the situation and they understood it. They planned an interview for the first day after my (supposed) return.

When my employer decided to keep me there for another month, I had to contact the headhunter, explain it and they rescheduled without issues.

I came back and, as pissed as I was, went to the interview and nailed it. Few days (and interviews later), I had a new job. By then, my current job knew nothing (yet), I was about to give my notice when something happened:

Right before lunch, my then manager, calls everyone and starts a speech saying there's "some people" who are lately lacking will and enthusiasm because, and I quote, "they clock in at exactly 8 am and clock out at 5pm without caring if there's other people still working". That was directed at me because I was pissed and started to simply follow my shift to the second. He continued rambling about how there's people who don't deserve to work there and other indirect attacks that clearly had my name on them.

I was going to give my two weeks notice that day, personally, to my boss, but the "meeting" got me so pissed that I decided to be pety about it:

Here, you can, instead, notify the ministry of employment online about your two weeks notice and they send an official notice to the employer in your place.

The boss found about it the same day he called me to offer me a raise. It goes without saying but he wasn't happy about the notice. He sent me home and told me to never come back. I took my stuff, went home and enjoyed my free days until I started on my current job.