Searching for a solvate that changes its solvation property
http://nvlpubs.nist.gov/nistpubs/jres/086/jresv86n2p181_A1b.pdf 
http://www.phasediagram.dk/binary/magnesium_sulfate.htm

Sodium sulfate hydrates,

http://iopscience.iop.org/0022-3727/41/21/212002/fulltext/ 
http://www.springerimages.com/Images/Chemistry/1-10.1007_s00269-008-0256-0-0

DOI:10.1209/0295-5075/102/28003 
http://ej.iop.org/images/0295-5075/102/2/28003/Full/epl15377f5_online.jpg 
http://www.phys.tue.nl/nfcmr/PhD-Saidov-2012.pdf

====

http://patentimages.storage.googleapis.com/US7638109B2/US07638109-20091229-D00001.png 
http://www.genchem.com/properties.asp 
sodium carbonate