I can tell you that developer salaries are growing. I have tried telling my senior management that the average senior developer salary in Boston will go from 120k in 2014 to 140k by 2017. I don't think that 16% can be called "exploding", since it's just 5% y-o-y, but it's definitely growing faster than the rest of the economy, and one of the few jobs where "real income" is growing.
Finally, my observation is that the biotech boom in Boston has created unique housing pressure in Boston, particular South Boston, Cambridge and the North End (East Boston is the only affordable place). So many biotech IPOs in the area have created newfound millionaires over night, and helped support a housing boom in the area. Combine this with DraftKings, Wayfair, Buildium, Amazon acquiring Kiva Systems, Samsung acquiring LoopPay, and other major tech companies coming into the area over the last 5 years, and you suddenly have markets where there is huge competition for labor but really expensive housing. This necessarily entails salary hikes or relocation. Relocation requires the board to negotiate with other states to relocate talent, which is always treacheous for high end white collar jobs.
If you want metrics to validate your assumptions, I recommend using CareerBuilder rather than these newer places like Hired.com. CareerBuilder has great analytics tools which show you where your salary offerings rank competitively.
Also, I can say that I don't think our problem is really salary, so much as the fact that so many developers lack adequate training in _engineering_, which entails solving real problems related to total cost of ownership, stability/uptime, throughput, etc. If you work for a _product company_, it is very hard finding these kinds of engineers, for two reasons: (1) they tend to become specialists or architects, but your replacement reqs are generalist roles like full-stack developers (2) 60% of all developers are contractors, and never acquire sufficient depth to solve real hard engineering problems.
End note: I work for erecruit, enterprise staffing software. I have tons of data about the market.