> It was much quicker and easier to get the agar to 90C temperature by putting it in a microwave for 40s at 900W

Agarose gels in molecular biology labs are prepared in a similar way. (Agarose is the main component of agar.)

It’s also the main reason those microwaves are so gross!

Since it’s relatively thick, boiling solution sputters everywhere and is—-at best—-partially cleaned up by harried scientists. Use a big container and try not to overshoot the temp.