Counterexample of Sobolev Embedding Theorem $W^{1,n}(\mathbb{R}^n) \nsubseteq L^\infty (\mathbb{R}^n)$

Question

I am looking for a counterexample of Sobolev Embedding Theorem $W^{1,n}(\mathbb{R}^n) \nsubseteq L^\infty (\mathbb{R}^n)$.

I feel that somehow the log(log()) function could provide an example but I am not figuring it out explicitly.