Magento 2 Module Development - Code changes only work after VM reboot

Question

I created a small module and it works great. But if I then make changes to the code, they only take effect after I restart the VM. There must be an easier/faster way?! It's not a big or error-prone change either. I'm writing something to the log file and want to write another line underneath it.

This is working:

$this->logger->info("1: observer working");  

This isnt working until reboot:

$this->logger->info("2: observer after");