Full Metal Alchemist was led to an outside-the-manga conclusion and was later rebooted as FMA Brotherhood, which ended the series according to the Manga's whims.
BTOOOOM ended where the manga was and is waiting for more chapters to build before it makes its season two.
Titan's manga is nowhere near finished, and they've only announced this one season. Either they'll stop where the manga is/a little behind it and not do another season until time's built, or they'll make an ending while the manga goes on, and assumedly its popularity will necessitate a rebooted true ending like FMA did.