Reaction between chlorobenzene and sodium methoxide to produce anisole
Chlorobenzene is inert towards most forms of nucleophilic substitution. In particular:

A $\mathrm{S_N1}$ mechanism is not likely here because the carbon is $\mathrm{sp^2}$ hybridised, the $\ce{C-Cl}$ bond is strong, and the dissociation of $\ce{Cl-}$ is therefore not very likely.
$\mathrm{S_N2}$ substitution doesn't occur because 1) the $\ce{C-Cl}$ bond is strong 2) the $\sigma^*$ orbital is in the middle of the ring and is inaccessible to a nucleophile.
The $\mathrm{S_NAr}$ mechanism could be followed if there is an electron-withdrawing group ortho or para to the chlorine atom, but in chlorobenzene, there is no such EWG.

I would like to suggest the possibility of a benzyne mechanism, i.e. an elimination-addition mechanism. The elimination step follows an $\mathrm{E1_{cb}}$ mechanism:

The benzyne intermediate is very electrophilic and nucleophilic attack by methoxide ion proceeds rapidly to give anisole.

Although this reaction is well-documented with both $\ce{NaOH}$ and $\ce{NaNH2}$, I can't find any real-life examples with $\ce{NaOMe}$. Most examples of chlorobenzene → anisole reactions involve some kind of catalyst. However, if it were to happen, it would probably occur via this parthway.