Is there a word to describe a person who is always curious?

Is there a word or phrase for describing a person who is always curious? Curiosiac?

Example usage (as requested by a comment):

The boy is such a ___, he asks questions all the time!

UPDATE

I appreciate all your answers, but my question was if there was any word - a noun - to describe a person of that kind, e.g. maniac, lunatic, weirdo, nerd, etc.


Solution 1:

Inquisitive, defined by Dictionary.com

  1. given to inquiry, research, or asking questions; eager for knowledge; intellectually curious:

"an inquisitive mind"

  1. unduly or inappropriately curious; prying

Solution 2:

Maybe someone who is "inquisitive"?

Inquisitive (adj): wanting to discover as much as you can about things, sometimes in a way that annoys people.

[Cambridge English Dictionary]

Solution 3:

Inquisitive is a good answer but also try pysmatic

Very questioning.

Also, quidnunc

a person who seeks to know all the latest news or gossip