Searching for maria casino gave its title as "Online Casino | FREE Casino | Maria Bingo", just like the title tag on the actual page. When instead searching for maria casino bingo that very same page instead had the title "Online Casino | Roulette - Blackjack - Casino ... - Maria Bingo".
There was an added "- Maria Bingo" suffix and we had no idea where that came from. A truly WTF moment for myself.
Turns out there is a clear and transparent reason for this – Google simply changes the title. They allegedly do this to try and make the title more relevant to the current search query.
In the video Matt explains that this only affects the representation of the page in the SERP. The real title itself should remain in full effect for calculating how well the page places for a specific search query.