Ask a question, get an answer. This is a book my teacher read to my class in the sixth grade. I think.
That would’ve been in 1982. All I remember is a boy who was a strange kid
at school turned out to be a martian. There’s an adventure. Perhaps it’s
narrated by the boy’s friend. It ends with him flying away in a UFO. I’ve
always wanted to read it again.

Could be Alan Mendelsohn, The Boy From Mars by Daniel Pinkwater. It's
been awhile since I read it, but your details fit what I recall.
Everything by Pinkwater is well worth reading, anyway, so it's worth a
look.

Book for Gender Variant/Non-Conforming Kids
Big Orange Splot makes the cut.

Books for Kids with Autism
Lizard Music makes the cut.

On Edward Lear
Pinkwater's blurb on the back fold shares his initial discovery of Lear. Like Pinkwater, I remember my first time, so to speak. I found a tattered collection of Lear limericks on a weekly library search and promptly proceeded to read anything with his name on it. Then I read them all again. And again.

Review of Mrs Noodlekugle
Mr. Pinkwater writes a light story with lots of action and silly characters and it's fun to read. If you have a child who likes make believe, they will love this book.

(I despise silly characters and make believe, so I guess I should avoid this book at all costs.)

Another review
READ IT IF:
You like the idea of magical old ladies, talking cats and blind mice.
You like whimsical books.
You like cute illustrations that make it easier to imagine the story.

Magical Old Ladies...