Consider Hong Kong as an (extreme) example, where leaving the city means emigrating to another country with another language etc. (yes, HK is technically a Special Administrative Region of China, but can be considered standalone in this respect).
The median apartment price/income ratio here is 18, compared to a US average of 3.9 (the highest cities in the linked article are 13) [1].
These ratios also don't consider what you actually get. The average size of new apartments sold this year in HK was 610 square feet at an average price of US$1.8m and one new development offers apartments the size of Tesla Model X for ~US$500,000 [0].
If you want to go larger, the per square foot cost goes up. At the extreme end, consider a 4000 square foot townhouse that costs US$21,190/square foot [2].
A more ridiculous example is perhaps the sale of a car park earlier this year for US$600,000.
For reference, the median household income is ~US$38k. [1]
Unfortunately those with the most housing affordability issues are those that are least capable of leaving.
[0] https://www.bloomberg.com/news/features/2017-06-14/you-can-b...
[1] http://www.demographia.com/dhi.pdf
[2]http://time.com/4752342/worlds-most-expensive-house-square-f...